Pressure Controls type KPU REFRIGERATION AND AIR CONDITIONING Technical leaflet
Contents Page Introduction... 3 Features... 3 Approvals... 3 Materials in contact with medium... 3 Technical data... 4 Ordering... 4 Contact systems and application... 5 Design / Function... 6 Terminology... 7 Setting... 7 Dimension and weight... 8 2 Danfoss A/S (IC / MC, mr), 09-2004
Introduction KPU pressure controls are designed for use in refrigeration and air-conditioning systems to protect the systems from excessively low suction pressure or too high discharge pressure. They can also be applied to start and stop compressors and the fans of air-cooled condensers. KPU pressure controls, in single and dual versions cover a comprehensive range of applications, and are designed for use with fluorinated and nonaggressive refrigerants. Features Snap action electrical contacts minimize chatter, bounce, and wear, and ensure longterm electrical and mechanical reliability The fail-safe dual bellows used in KPU 6 and KPU 16 prevent refrigerant loss and enable primature cut-out when a fault occurs SPDT or SPST switch a in single control models. SPST or SPDT with high-low pressure signal in dual control models Manual trip allows electrical function test without tools Easily replaces Johnson Controls and Ranco products Wide pressure range: from low pressure KPU 2 with narrow differential to KPU 6 and KPU 16 for high pressure refrigerants (R 410A, CO 2 ) Automatic, manual or convertible reset versions available Vibration and shock resistant Integrated bellows-spring assembly, computer design for maximum accuracy Repeatability less then 0.1 psi drift, even after 400 000 cycles Approvals cs UL listed for USA and Canada, file E31024 according to UL 873 CE-marked in accordance with EN 60947-4/-5 KPU6W, KPU6B, KPU16W and KPU16B: CE-marked in accordance with PED 97/23/EC, category IV, safety equipment - EN 12263 Materials in contact with medium Unit type Material KPU 1, 2, 5, 15 Tin bronze, no. 2.1020 to DIN 17662 Nickel plated free cutting steel, no. 1.0737/ 1.0718 to DIN 1651 KPU 6 and 16 Stainless steel bellows KPU with capillary tube Copper SF-CU no. 2.0090 to DIN 1787 3
Technical data Ambient temperature -40 to 122 F (+ 175 F for max 2 hours) Maximum working pressure Low pressure (LP) controls KPU 1, KPU 2 and LP side of KPU15, KPU16: 250 psig High pressure (HP) controls KPU 5 and KPU15 on HP side: 510 psig KPU 6 and 16 on HP side: 675 psig Maximum testing pressure Low pressure (LP) controls KPU 1 and KPU 2: 290 psig High pressure (HP) controls KPU 5 and KPU 15 on HP side: 530 psig KPU 6 and 16 on HP side: 725 psig Cable entry 7/8 cable entry for ½ male pipe thread connection (conduit boss) Contact load Alternating current: FLA = 24 A @ 120 Vac 24 A @ 240 Vac LRA = 144 A @ 120 Vac 144 A @ 240 Vac LRA is rated for make only Direct current: 240 V DC: 12W pilot duty Alternating current (acc. to EN 60947) AC1: 16 A, 400 V AC3: 16 A, 400 V AC15: 10 A, 400 V Direct curent: DC 13: 12 W, 220 V, control current Wire dimension: 10 AWG maximum Enclosure NEMA 1 acc. to NEMA Standard Publication 250-1997 Ordering Pressure controls for fluorinated refrigerant Pressure Control type Low pressure (LP) High pressure (HP) Reset Range psig psi Range psig psi Low pressure LP High pressure HP Contact type 1/4" male flare Code no, 36" cap. tube w. 1/4" flare nut Low KPU 1 6" to 108 10 to 60 Aut. A 060-5231 060-5233 Low KPU 1 6" to 108 10 to 60 Aut. B 060-5236 Low KPU 1B 28" to 100 10 fixed Man. A 060-5232 060-5234 Low KPU 2 6" to 73 6 to 30 Aut. B 060-5237 060-5235 Low KPU 2 6" to 73 6 to 30 Aut. A 060-5239 060-5240 Fan cycling KPU 5 100 to 465 25 to 85 Aut. B 060-5241 060-5242 Dual KPU 15 6" to 108 10 to 60 100 to 465 60 fixed Aut. Aut. C 060-5247 060-5248 Dual KPU 15B 6" to 108 10 to 60 100 to 465 60 fixed Aut. Man. C 060-5249 060-5250 Fail-safe controls for high pressure refrigerants (R410A, CO 2 ) PED approved according to EN 12263 Pressure Control type Low pressure (LP) High pressure (HP) Reset Range psig psi Range psig psi Low pressure LP High pressure HP Contact type 1/4" male flare Code no, 36" cap. tube w. 1/4" flare nut High KPU 6W 100 to 600 58 to 145 Aut. A 060-5243 060-5245 High KPU 6B 100 to 600 60 fixed Man. A 060-5244 060-5246 Dual KPU 16W 6" to 108 10 to 60 100 to 600 60 fixed Aut. Aut. D 060-5251 060-5252 Dual KPU 16B 6" to 108 10 to 60 100 to 600 60 fixed Conv. Conv. D 060-5253 060-5254 4
Contact system and application A B SPDT Switch type Switch action Application 1. Terminals 1-4 close high and open low 1. Low pressure cut-out Terminals 1-2 can be used as low pressure alarm 2. Terminals 1-2 open high and close low 2. High pressure cut-out Terminals 1-4 can be used as high pressure alarm Terminals 1-4 close high and open low 1. Low pressure cut-out 2. Condenser fan cycling control C SPST Dual pressure control employs an SPST switch that is open when either high or low pressure beyond the control setting is sensed on the two bellows sensing elements of the control Dual pressure control Protects the system against too low suction pressure and against too high discharge pressure D SPST, dual pressure (LP/HP) Contact opens on pressure drop below LP set point (turns on the LP signal light) and on pressure rise above HP set point (turns on HP signal light). Contact action is controlled by two bellows sensing elements. Note: max. contact D rating is 50 VA Dual pressure control. Protects the system against too low suction pressure (LP cut-out signal on terminal B) and against too high discharge pressure (HP signal on terminal D). SPDT with LP/HP signal Load Signal Bellows movement on pressure drop Bellows movement on pressure rise Pressure control setting with convertible reset Low pressure Manual reset 1) Automatic reset Automatic reset Manual reset High pressure Manual reset 1 ) Manual reset Automatic reset Automatic reset 1) Factory setting 5
Design and function Key sketch of KPU kontrol 1. Low pressure (LP) setting spindle 2. High pressure (HP) setting spindle 3. 4. Low pressure main spring 5. High pressure main spring 6. spring 7. Ground terminal 8. Cable entry 9. Bellows 10. LP connection 11. HP connection 12. Control terminals 13. Reset button 14. Arm 15. Switch 16. Tumbler 17. Locking plate 18. Contact housing 19. Damping device Switch function The switch in KPU control has a snap-action function and the bellows moves only when cut-in or cut-out set point is reached. This design has following advantages: - high contact load - ultra-short bounce time - long mechanical and electrical lifetime - high resistance to pulsation and vibrations Reset Version with automatic reset cut-in again automatically when the pressure falls or rises to the set point minus differential. Version with manual reset have to be cut in manually with external reset button when the pressure in KPU 1 rises min. 10 psi above the set point value, and in KPU 6 falls min. 60 psi under the set point value. All KPU pressure controls operate independently of changes in ambient temperature around the control. Therefore the setting for cut-out pressure and differential stay constant unless the permissible ambient temperature is exceeded. KPU single (KPU 1, 2, 5, 6) without front cover KPU dual (KPU 15, 16) without front cover Fail-safe bellows concept in KPU 6 and high pressure side of KPU 16. 1. Pressure connection 2. Regulating bellows 3. Outer bellows KPU 6 and high pressure side of KPU 16 have double bellows: an outer bellow and a regulating bellow. When system pressure exceeds the set value, the KPU will automatically stop the system. The double bellows system prevents the loss of charge in the event of bellows rupture. Rupture in the outer bellows causes the control cut-out pressure to fall about 40 psi under the set value, thus providing fail-safe function. 6
Terminology Set point A predetermined value to which a control is adjusted and at which it performs its intended function Reset 1. Manual reset A unit with manual reset can only be restored to operational mode by activating the external reset button. 2. Automatic reset A unit with automatic reset is restored to operational mode automatically. 3. Convertible reset A unit with convertible reset can be adjusted for either automatic or manual reset. Maximum working pressure The maximum permissible pressure for safe functioning of a refrigeration system or any of its parts. Maximum test pressure The maximum pressure applied in strength or leakage tests on refrigeration systems or components thereof. is the number of psi (or bar) by which cut-in and cut-out set points are separated Snap function A specific contact force is maintained until snap is initiated. The time over which contact force reaches zero is a few milliseconds; therefore, contact bounce cannot occur as a result, for example, of slight vibrations before cut-out. The snap-action contact system will continue to function even when micro-welds are created between the contacts during cut-in. The force created to separate the contacts is strong, and instantly shears off all contact surface welds that have been created as the result of cut-in action. These design features ensure that the cut-out point of the KPU control remains very accurate and completely independent of the magnitude of the current load. Fail-safe control A control is fail-safe if it has the capability to remain in a safe condition or transition to a safe condition when a fault occurs. FLA -Motor Full Load Amperes The current rating, in amperes, of the motor when a full load is applied to it for work being done. LRA - Locked Rotor Amperes The current drawn, in amperes, by an electric motor with the shaft or rotor stopped and locked in position. Setting Cut-in and cut-out pressures for both LP and HP sides of the system should always be checked with an accurate pressure gauge. Low Pressure setting for controls with automatic reset 1. Set the LP cut-in pressure on the CUT-IN scale (range scale). One rotation of the low pressure spindle ~ 5.2 psi for KPU2 and ~6.8 psi for KPU1 2. Set the LP differential on the DIFF scale. One rotation of the differential spindle ~ 3.2 psi for KPU2 and 2.9 psi for KPU1. Note: The LP cut-out pressure is LP cut-in pressure minus differential value. The LP cut-out pressure must be above absolute vacuum (Pe = 29.5 in. Hg). High pressure setting for controls with automatic reset 1. Set the HP cut-out pressure on the CUT-OUT scale. One rotation of the HP spindle ~ 22 psi for KPU5 and ~ 28 psi for KPU6. 2. Set the HP differential on the DIFF scale. One rotation of the differential spindle ~ 5.3 psi for KPU5 and ~ 8.6 for KPU6. Note: The HP restart pressure is equal to HP cut-out pressure minus differential. Pressure controls with manual reset Set the cut-out pressure on the CUT-OUT scale (range scale). Low pressure controls can be manually reset when the pressure is above the cut-out pressure plus the differential. High pressure controls can be manually reset when the pressure is below cut-out minus differential. 7
Dimensions and weight KPU with flare connection KPU single KPU dual Approximate weight: 0.765 lb Approximate weight: 1.19 lb KPU with capillary tube KPU single KPU dual Approximate weight: 0.91 lb Approximate weight: 1.5 lb All controls are supplied with universal mounting bracket and mounting screws as standard accessory. Approximate weight of the bracket and mounting screws: 0.615 lb 8 Danfoss A/S (IC / MC, mr), 09-2004